The chief legal advisers to several US states are considering a court challenge to President Donald Trump's executive order, which restricts people from seven Muslim-majority countries from entering the United States.
A lawsuit brought by states would mark a serious strengthening of the opposition to Mr Trump's controversial order, which has sparked protests across the country since it was signed last week.
“We do believe the executive order is unconstitutional,” said Hawaii's attorney general Douglas Chin. declining to give any more detail.
“There certainly are conversations underway,” added Joe Grace, a spokesman for Pennsylvania attorney general Josh Shapiro.
Democrat attorneys general have long been expected to lead a fierce resistance against Mr Trump, in the same way Republican legal chiefs opposed former President Barack Obama.
But it remains unclear how many states would join an effort to have the executive order ruled unconstitutional and he three states who have so far expressed intent might also ultimately decide not to file a lawsuit.
Mr Trump has insisted that the order was “not a Muslim ban” and said the measures were long overdue.
Protesters have surrounded airports in the United States where people with valid visas or refugee status have been detained since Mr Trump signed the order.
A federal judge in New York ordered a stay on Mr Trump's deportation order, and said stranded travellers could remain in the country.
The American Civil Liberties Union, which sought the emergency court order, said it would help 100 to 200 people with valid visas or refugee status who found themselves detained in transit or at US airports after Mr Trump signed the order.
The Department of Homeland Security said in a statement it would comply with judicial orders but that Mr Trump's immigration restrictions remained in effect.
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